Percentage Calculator — % of, % change, ratio
Three-in-one percentage calculator: X% of Y, X as a % of Y, and % increase/decrease. Instant, client-side.
What is X% of Y?
X is what % of Y?
% change from X to Y
How to use
- 1 Pick the calculation you need — three common percentage problems are shown.
- 2 Type your numbers; the answer updates instantly.
- 3 No rounding surprises — results show up to 6 significant digits.
Why use this tool
- Three calculators in one: percent of a number, ratio as a percent, and percent change.
- Instant, no signup, runs entirely in your browser.
- Handles decimals and negatives.
Frequently asked questions
How do I find X% of Y?
Multiply: (X ÷ 100) × Y. For example, 15% of 200 = 0.15 × 200 = 30.
How do I work out what percent X is of Y?
Divide and multiply by 100: (X ÷ Y) × 100. For example, 30 of 200 = (30 ÷ 200) × 100 = 15%.
How is percentage change calculated?
((new − old) ÷ |old|) × 100. A result with a minus sign is a decrease.
Is my data sent anywhere?
No. Everything runs locally in your browser — nothing is uploaded.
What is Percentage Calculator?
A percentage calculator computes the three most common percentage problems: a percentage of a number, one number as a percentage of another, and the percentage change between two numbers.
Features
Three percentage modes
"X% of Y", "X is what % of Y", and "% change from X to Y" — all on one screen.
Live results
Answers update instantly as you edit any field.
Free & private
Runs on your device — no signup, nothing uploaded.
Example
Input
What is 15% of 200?Output
30Common use cases
-
1
Discounts & tips
Work out a sale price or a tip as a percentage of the total.
-
2
Grades & scores
Find what percent a score is of the maximum.
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3
Growth & change
Compute the percent increase or decrease between two values.
Zerethon's percentage calculator solves the three common percentage questions in your browser: what is X% of Y, X is what percent of Y, and the percent change from X to Y. Each is computed live as you type. Everything runs client-side — nothing is uploaded.
- Category
- Math
- Pricing
- Free
- Privacy
- Browser-based
- Signup
- Not required
References
- Percent — Wolfram MathWorld — Wolfram MathWorld
- Percentage — Wikipedia
Privacy
Your data never leaves your browser unless explicitly stated. Percentage Calculator runs entirely client-side — no server upload, no logging, no tracking of your input.
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